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l. B. BRISTOW.

f LIFTING MCK.

APPLICATION FILED SEPT. 19. |911.

l 1,317,857. 4 Pateted Oct. 7,1919.

2 SHEETS-SHEET l.

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l. B. BRISTOW.

LIFTING JACK.

APPLlcArmN FILED sEPT.19. 1911.

1 ,3 1 7, 857 Patented Oct. 19.

2 SHEETS-SHE Y JAMES i3. BRIsTow, or MONROE oI'rY, MISSOURI.;

y LIFTING-IAOK.

Specification of Letters Patent.

Patented oet. 7,1919.

Application filed September 19, 1917. Serial No. 192,137.

vTo all whom t may concern Beit known that I, JAMES B. VBiris'row, a, citizen of the United States, residing at Monroe City, in the county of Monroe, State of Missouri, have inventedl certain new and useful Improvements in'Lifting-Jacks; and I do hereby declare the following to be a full, clear, and exactdescription of the invention, such as will enable others skilled in the `art to which it appertains to make and use the same.

This invention relates to liftingfjacks. A

is to provide he object ofthe invention an improved form of lifting jack for use in j acking up vehicles, particularly in garages where motor vehicles must be lifted for repair 1n greatnumbers. In storage and repair garages, motorV vehicles of all makes" are indiscriminately brought together, and repairmen and cleaners must place jacks underuaxles and other parts which seldom` stand in the same height. "Those'jacks which are now inthe market `and known to me v reference being had to the v,ofan oil cushion n Yheight of the part to beV jacked up, andjupon must be manually adjusted to the particular vehicle or part to be lifted before- `the jack` fing action can beA begun, and it is the intention of this invention to provide a jack which automatically accommodates itself to the height of the part tobe lifted andis then automatically locked at the proper height so that the jacking action can be begun. i

-More particularly, it is the objectof thisK4 invention to provide an automatically adj ustable jack which depends upon the height for itsv adjustment to the the pressure exerted by the object to be lifted for the locking of the jacking element/at the proper height.

With the above objects in View, and such others relating to the details of construction as may hereinafter appear, my invention will now be fully set forth and described,

accompanying drawings.

In the drawings Figure 1 is a side elevation,

Fig. 2 is a longitudinal section, Y

Fig. 3 is a view showing the device adjusted, prior to. the lifting action, Y

Fig. 4 is a longitudinal section showing the device supporting an axle,

Fig. 5 is a section on line 5-'5 of Fig. 2, and

Fig. 6 is a section on line 6 6 of Fig. 2.

Referring more particularlyto the drawings, 1 represents a preferably cylindrical oil chamber which is supported upona pair of jack wheels 2. Operative within the chamber or cylinder 1 is a piston 3 which is held in place by means of a bushing plug 4l and has its head suitably packed or capped as at 5, to prevent the passage of oil past the head. TheV exposed end of the piston 3 is provided with a suitable saddle 6 for the engagement of an axle or other part to be lifted.

At its lower end, the cylinder 1 extends to one side in a reservoir 7 which is divided from the cylinder by means of a partition A8 centrally provided` with a valvecasing 9.

The: casing 9 includes a seat l0 which opens toward Vthe cylinder 1, and a spider or stop seat 10 has a ste-ni 13 which projects through f the seat, andbehind the latter is surrounded by a coil Vspring 14 whichfbears between the' valve .head anda grid15 formed across the rear of the `lvalve chamber,l so that the valve is normally unseated thereby. The expansive ability `of thespring 14 is such that it willA hold the valve 12 ofi'l of its seat under a certain predetermined pressureV upon .the piston 3, but will close when that pressure is exceeded. Y -V 1 The chamber or reservoir 7 is capped by a closure fitting 16 which forms the head'of a hollow, handle 17. VThe handle 17 extends from theV head 16 ina downwardly arched length, so that a foot portion 18 rests upon theground surface when the jack stands in lifting` position. As above stated, the handle 17 is hollow, and furthermore, is provided with an air connection 19, by means of which air under pressure may be yblown into the handle. When the partsare assembled, the handle 17 forms a continuation of the reservoir 7 and when air is blown into the handle the pressure assists the spring 14 in holding the valve 12 off of its seat. And furthermore, insures the unseating of the valve as soon as la supporting partis removed from the piston. Theair which is blown into the handle'l7 need not be of any greater pressure than can be blown in by the application ofthe mouth to the air inlet 19, a one pound pressure beingusually all that is needed.

.ward Vjmowniuent of In assembling the above described device, the bushing 4 is removed, together withhthe piston, and the chamber 1 and reservoir 7 lill with oil to the point where room isjust provided for the `piston 3 and the return of the bushing 4. Then, the air inlet 19 is opened and air forced therein under sufliclent pressure to insure the unseating of the valve 12 when the jack is not in use. Then, in order to elevate a weight, the jack is tipped forwardly until the saddle 6 can be brought below the axle or another part to be lifted. Then, the handle 17 is carried gradually and steadily downward until the piston 3 has been carried a suiiicient distance into the cylinder 1, by its bearingupon the axle. When the proper point of adjustment has been reached, the handle 17 is given a sudden downward jerk. This causes a quick increase in the pressure upon the saddle v6, and consequently causes the piston 3 to react upon the oil cushion withinthe cylinder 1 to close the valve 12 against the spring 14. Continued downthe handle 17 will then cause the change in the position of the j ack from thatshown in Fig.g3 to the operative position of Fig. 4, the continuous applicationof the weight of the body lifted to the piston 3 holding the valve 12 upon its seat.

Asv soon as the jack is removed from below the lifting body and the pistonis relieved of its weight, the air pressure inthe upper end of the handle 17, together with ,the `action of the spring 14 will open the valve 12, thereby placing the jack in readiness for adjustment to another vehicle. If it is desired to maintain the jack at a constant position of adjustment, as when it is used in lifting a number of cars of the same copies of this patent `may be obtained for type, it is placed in its lifting positionbelow the first ear. "Then, the air inlet 19'is opened to permit the escape of the, air.

Then, when the jaclr'is removed from under l the first car, the valve 12 will not open, and consequently the piston 3 will remain in the position of adjustment, and can be thus maintained until the air pressure is Vrestored, in the handle V17.

From the foregoing description it will be apparent that the improved form of jack which l have evolved will save a greatdeal of labor and time in garages and shops where automobiles and other weights must be frequently lifted, since by the same action which lifts the weight, the jack can be adj usted to theheight of the weight to be elevated, the user being thereby relieved of the necessity of stooping below the car or to the jack body for a preliminary adjustment for operating the 'lifting handle.

What l claim as my invention is A lifting jaclr comprising a cylinder, a wheeled support for one end of the cylinder, a .piston slidable in the cylinder, said piston projecting from the other end of the cylinder, al Vreservoir in communicaV tion: with the cylinder anda valvefor controlling the flow of fluid between said cylinder and reservoir, said valve being normally a stein 'for openand adapted toclose upon the occur:

five cents each, by addressing `the Gommissioner `oi! 'Patents Washington, D. C. 

